1. Field of the Invention
The invention relates to railway rolling stock and consists particularly in a system for transporting freight carriers including highway semi-trailers and receptacles such as demountable containers and merchandise racks by rail.
2. The Prior Art
Systems of moving highway semi-trailers by rail have generally utilized substantially conventional flat cars of sufficient length to support the full length of one or two highway semi-trailers with the highway wheels of the semi-trailers resting on the car deck and the king pin secured to an upstanding pedestal-mounted fifth wheel on the car deck. Such systems have numerous disadvantages in that the great over-all height of the flat car and the semi-trailers with their complete running gear creates clearance problems, particularly in tunnels, and provides a vehicle with a very high center of gravity and correspondingly subject to high overturning moments. Further, much excess weight is present in the form of the full-size railway flat car with its necessarily heavy underframe, trucks, draft gear and brake equipment.
The conventional equipment requires circus-type loading in which a train of flat cars are connected by bridges with a ramp at the forward end and the semi-trailers are successively backed onto the flat cars by tractors which must traverse the full length of the train to load the rearmost trailer. Atempts have been made to lower the over-all height by providing highway wheel pockets in the flat car decks or providing depressed center flat cars arranged to receive the highway wheels in the center depressed portion. In connection with the latter arrangement turntables and transfer tables have been provided in the center depressed portions of such cars to receive the highway wheels and to permit side loading, thus avoiding the disadvantages of circus-type loading. Although the last-mentioned arrangements have partially solved the over-all height and loading problems, they still require the use of a relatively heavy double truck flat car or depressed center car with turntable or transfer tables.
Further attempts to solve the problem have provided for the elimination of the conventional supporting flat car by providing smaller four-wheel trucks, each equipped with a fifth wheel support for engaging the king pin and supporting the front end of one highway trailer and means for supporting and blocking the highway wheels on an adjacent semi-trailer, utilizing the railway truck frame as the connecting link between adjacent trailers and forming trains from such railway trucks and trailers, as disclosed in L. G. Schoen U.S. Pat. No. 2,992,621 and F. S. Macomber U.S. Pat. Nos. 3,576,167 and 3,610,168. In these three patents the positions of the fifth wheel pedestals and the highway wheel supporting means are fixed longitudinally of the rail truck, i.e., the fifth wheel pedestal is adjacent one end of the railway truck and the highway wheel-supporting structure is adjacent the other end of the rail truck. These arrangements require that the rail trucks be turned at each end of a run in order that the fifth wheel pedestal supports be at the rear of the rail truck and the highway wheel supporting means be at the forward end of the rail truck so that trains made up of trailers and the rail trucks can be operated with the forward ends of the trailers at the front. Additionally, since the spacing between the fifth wheel supports and the highway wheel supports on the rail trucks of these patents are fixed, in the event that a trailer with a longer than normal forward overhang and/or one with a longer than normal rear overhang were to be transported in end to end relation, they could not be mounted on a common rail truck.